It has been the product of ten years of intensive diplomatic lobbying and is billed as the best chance the world has yet seen to regulate a trade that kills hundreds of thousands every year.

But even before the ink was dry there was scepticism that the UN’s newly passed global Arms Trade Treaty (ATT) will have any palpable effect unless the world’s biggest weapons manufactures sign up.

The treaty, which was stalled last summer, was overwhelmingly approved late on Tuesday night at the UN and has been hailed as a landmark attempt to bring some sort of control to the sale of small arms, tanks and missiles – weapons which kill by far the largest percentage of people each year but remained unregulated.

Despite fierce opposition from Russia, China, Iran, North Korea and Syria over the inclusion of provisions banning sales to human rights abusers – and steep opposition from America’s gun lobby over a clause covering ammunition – the treaty was passed by 154 countries with 23 abstentions and three votes against. North Korea, Syria and Iran voted against the treaty whilst Russia and China abstained. The Obama administration voted in favour of the treaty in a snub to the gun lobby which recently managed to halt an attempt to curb the sale of semi-automatic rifles following a spate of spree killings.

David Cameron hailed the vote as “a landmark agreement” that would “ease the immense human suffering” caused by conflicts whilst groups like Amnesty International and Oxfam – who have long lobbied for the ATT – largely welcomed the wording of the document. But others were more sceptical. Campaign Against Arms Trade warned that the treaty would do little to curb the sale of arms to despotic regimes because it recognised that countries have entirely commercial reasons to export of arms.

"This treaty legitimises the arms trade,” said Ann Feltham, CAAT's Parliamentary Coordinator. “If governments are serious about ending the trade in weaponry, with its dire consequences for peace and human rights, they should immediately stop promoting arms exports."

Both supporters and critics are agreed that for the treaty to have teeth, the world’s major exporters will need to sign up – and ratify – the document. That is where the real difficulties will begin. Implementation is years away and there are no specific provisions to monitor its success.

In the US – the world’s largest arms producer – the National Rifle Association and nearly 50 senators have already said they will try to stop the treaty’s passage through the legislature. Russia and China – major weapons manufacturers with considerably looser domestic controls governing who they sell weapons to – have also yet to be convinced of the benefits of the ATT. Doing so will be key to the ATT’s success.

The global land mine ban, which began with a similar treaty in 1999, now has 160 countries signed up. But the world’s largest mine manufacturers, including the US, Russia, China, India and Pakistan, have refused to back it meaning landmines are still routinely available and used in conflicts.

If Russia signed up to the ATT it would be particularly difficult for Moscow to continue supplying arms to the Syrian regime which is in the midst of a civil conflict that has killed an estimated 70,000 people.

Anna MacDonald, head of arms control at Oxfam International, said the treaty should be considered a success despite its current shortcomings.

“This treaty won’t solve the problems of Syria overnight, no treaty could do that, but it will help to prevent future Syrias,” she said. “It will help to reduce armed violence. It will help to reduce conflict.”